Conventionally, apparatuses which can realize a paper-pencil relationship are known, in which a coordinate input apparatus capable of inputting coordinates is placed on the display screen of a display apparatus such as a CRT display, a liquid crystal display (LCD), or a projector so that operator's pointing or handscript by a pointing tool is displayed on the display apparatus.
There are coordinate input apparatuses of a type that uses a transparent input plate, including a resistive film type, an electrostatic type, and an ultrasonic wave type which propagates an ultrasonic wave to a coordinate input surface made of glass or the like. Some coordinate input apparatuses are of an optical type or type which detects a position by radiating a sonic wave into the air. In some coordinate input apparatuses of an electromagnetic induction (electromagnetic transmitting/receiving) type, a mechanism for calculating coordinates is placed behind a display apparatus while a transparent protective plate is placed in front of the display apparatus, thereby constructing an input/output integrated information device.
Such information devices have been used for electronic notepads at first. Along with an increase in the size of display apparatuses, information devices such as a relatively large pen input computer are also becoming popular. Such information devices are combined with wide-screen display apparatuses such as front projectors, rear projectors, or PDPs and used as, e.g., presentation apparatuses or video conference systems. For display apparatuses such as wide-screen liquid crystal displays or PDP displays, image quality improvement and cost reduction are still progressing. As satellite broadcasting and the like are switching to digital broadcasting systems, the specifications and forms of TV sets are also entering a transitory stage.
These wide-screen display apparatuses are replacing, e.g., whiteboards or electronic blackboards used in offices and are used at meetings or briefings by displaying material data that are prepared in personal computers in advance on the wide-screen display apparatuses. In this case, information displayed on the wide-screen display apparatus can be updated by an operator or a person present by directly touching the screen like a whiteboard so that, e.g., the display contents on the display screen can be switched by controlling the personal computer.
However, large-scale input/output integrated systems of this type have the following problems.
When a briefing assuming many participants or use environment through a network is taken into consideration, it is more preferable that, e.g., a questioner be able to operate the screen from his/her position by remote control or obtain information from the network from his/her position, as needed, in addition to control of a personal computer by causing an operator to directly touch the screen.
When a conventional apparatus of this type is used to perform input (remote control) from a position spaced apart from the screen, a relative coordinate scheme is used, in which the cursor moving amount is calculated on the basis of the differential value from the preceding coordinates, like a mouse that operates a computer.
Hence, the operator checks the current cursor position displayed on the screen, moves the cursor from that position to a desired position, and further moves the cursor while drawing a graphic pattern or the like.
More specifically, if the system turns on/off a signal to be transmitted to the coordinate input apparatus main body by pressing a button on a coordinate input pointing tool, the drawing operation is performed by repeating cursor movement, drawing (cursor movement), stop, cursor movement, and drawing (cursor movement) by turning on/off the switch.
However, the stroke amount by operation (by moving the hand) and the cursor moving amount are in a 1:1 correspondence (i.e., when the input device is moved by 10 cm, the cursor on the screen also moves by 10 cm) even when ten input position is far apart from the screen. When the operator wants to input a stroke long relatively to the screen, i.e., when the operator wants to perform one stroke operation without transmission stop operation, he/she needs to do a large action although the screen size seems to be relatively small for him/her because of the distance between the screen and the input position, resulting in considerable difficulty in input operation.
In some systems, the cursor displayed on the screen is moved by operating cursor keys. Such a system is excellent in operability for cursor movement. However, it is not always suitable in drawing a character or graphic pattern.